From: Konrad Meyer <konrad@...>
Date: 2007-11-23T13:39:02+09:00
Subject: Re: syntax Float equality within epsilon

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Quoth Phrogz:
> On Nov 22, 1:38 am, unbewusst.s...@weltanschauung.com.invalid (Une
> B=E9vue) wrote:
> > i need to test float numbers within an epsilon, then i've extended the
> > Float clas like that :
> >
> > class Float
> >   def =3D=3D=3D( aFloat, eps =3D 1.0e-10)
> >     begin
> >       clazz =3D aFloat.class.to_s
> >       raise "Argument \"#{aFloat}\" must be a Float (being of
> > #{clazz})." if clazz !=3D "Float"
> >       ( self > aFloat - eps ) && ( self < aFloat + eps )
> >     rescue
> >       puts "An error occurred: #{$!}"
> >       nil
> >     end
> >   end
> > end
> >
> > this works as expected except when i want not to use the default value
> > for eps where i couldn't find the correct syntax :
> > a =3D 1.000000001
> > b =3D 1.00000000012
> > p ( a =3D=3D=3D( b, 0.001) ).to_s
> > gave me :
> > [...] syntax error, unexpected ')', expecting tCOLON2 or '[' or '.'
> > p ( a =3D=3D=3D( b, 0.001) ).to_s
> >                     ^
> >
> > why ???
>=20
> Some operator methods have syntax sugar that prevents them from taking
> multiple arguments using simple syntax. You can get around this,
> albeit with a slightly less elegant syntax:
>=20
> irb(main):013:0> class Float
> irb(main):014:1>   def =3D=3D=3D( a, b )
> irb(main):015:2>     p a, b
> irb(main):016:2>   end
> irb(main):017:1> end
> =3D> nil
> irb(main):018:0> a =3D 5.4
> =3D> 5.4
> irb(main):019:0> a.send( :=3D=3D=3D, 42, 73 )
> 42
> 73
> =3D> nil
>=20
> If this is a case you'd use often, I suggest simply giving it a normal
> method name. that you can call without using #send

Or you could use "normal" method call notation:

  irb(main):009:0> a.=3D=3D=3D(32, 73)
  32
  73
  =3D> nil

Regards,
=2D-=20
Konrad Meyer <konrad@tylerc.org> http://konrad.sobertillnoon.com/

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